This invention relates to a probe comprising multifunctional electrodes for simultaneous determination of the concentrations of specific ions and gases in a fluid sample. The invention is primarily exemplified in a probe for determining the partial pressures of carbon dioxide and oxygen gases and pH or hydrogen ions and bicarbonate ions in a fluid sample where the term "fluid" means liquid or gaseous.
The probe to be described herein is intended for analysis of various fluid samples but it is particularly useful for analyzing blood in a blood vessel since the probe is small and can perform multiple analytical functions with only a single invasion of the vessel.
There are probes in the prior art for sensing a single constituent such as pH or hydrogen ions and carbon dioxide and oxygen partial pressures, respectively, in a fluid sample. Probes for measuring pH are described in U.S. Pat. Nos. 3,671,414, 3,709,810 and 3,726,777. Carbon dioxide probes are described in U.S. Pat. Nos. 3,673,069, 3,705,088, 3,709,812 and 3,719,576. A probe for measuring oxygen is described in U.S. Pat. No. 3,839,178. Methods for making probes are described in U.S. Pat. No. 3,798,750. These patents are assigned to the assignee of the present application.